Hydrocarbon feedstock containing higher molecular weight hydrocarbons is cracked by contacting the feedstock under elevated temperature conditions with a cracking catalyst whereby light distillates are produced. However, the cracking catalyst gradually deteriorates during this process. One source for this deterioration is the deposition of contaminating metals, such as nickel, vanadium and iron on the catalyst, which increase the production of hydrogen and coke. At the same time the conversion of those higher molecular weight hydrocarbons into gasoline is reduced.